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SubjectRe: general protection fault in tls_write_space
Jakub Kicinski wrote:
> On Tue, 13 Aug 2019 11:30:00 -0700, John Fastabend wrote:
> > Jakub Kicinski wrote:
> > > On Tue, 13 Aug 2019 10:17:06 -0700, John Fastabend wrote:
> > > > > Followup of commit 95fa145479fb
> > > > > ("bpf: sockmap/tls, close can race with map free")
> > > > >
> > > > > --- a/net/tls/tls_main.c
> > > > > +++ b/net/tls/tls_main.c
> > > > > @@ -308,6 +308,9 @@ static void tls_sk_proto_close(struct so
> > > > > if (free_ctx)
> > > > > icsk->icsk_ulp_data = NULL;
> > > > > sk->sk_prot = ctx->sk_proto;
> > > > > + /* tls will go; restore sock callback before enabling bh */
> > > > > + if (sk->sk_write_space == tls_write_space)
> > > > > + sk->sk_write_space = ctx->sk_write_space;
> > > > > write_unlock_bh(&sk->sk_callback_lock);
> > > > > release_sock(sk);
> > > > > if (ctx->tx_conf == TLS_SW)
> > > >
> > > > Hi Hillf,
> > > >
> > > > We need this patch (although slightly updated for bpf tree) do
> > > > you want to send it? Otherwise I can. We should only set this if
> > > > TX path was enabled otherwise we null it. Checking against
> > > > tls_write_space seems best to me as well.
> > > >
> > > > Against bpf this patch should fix it.
> > > >
> > > > diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> > > > index ce6ef56a65ef..43252a801c3f 100644
> > > > --- a/net/tls/tls_main.c
> > > > +++ b/net/tls/tls_main.c
> > > > @@ -308,7 +308,8 @@ static void tls_sk_proto_close(struct sock *sk, long timeout)
> > > > if (free_ctx)
> > > > icsk->icsk_ulp_data = NULL;
> > > > sk->sk_prot = ctx->sk_proto;
> > > > - sk->sk_write_space = ctx->sk_write_space;
> > > > + if (sk->sk_write_space == tls_write_space)
> > > > + sk->sk_write_space = ctx->sk_write_space;
> > > > write_unlock_bh(&sk->sk_callback_lock);
> > > > release_sock(sk);
> > > > if (ctx->tx_conf == TLS_SW)
> > >
> > > This is already in net since Friday:
> >
> > Don't we need to guard that with an
> >
> > if (sk->sk_write_space == tls_write_space)
> >
> > or something similar? Where is ctx->sk_write_space set in the rx only
> > case? In do_tls_setsockop_conf() we have this block
> >
> > if (tx) {
> > ctx->sk_write_space = sk->sk_write_space;
> > sk->sk_write_space = tls_write_space;
> > } else {
> > sk->sk_socket->ops = &tls_sw_proto_ops;
> > }
> >
> > which makes me think ctx->sk_write_space may not be set correctly in
> > all cases.
>
> Ah damn, you're right I remember looking at that but then I went down
> the rabbit hole of trying to repro and forgot :/
>
> Do you want to send an incremental change?

Sure I'll send something out this afternoon.

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